Marjoram (Origanum majorana L.) belongs to the Lamiaceae family of plants is common in most parts of the world as a medicinal plant used [1]. Serendipita indica (previously known as Piriformospora indica) is an endophytic fungus that forms symbiotic associations with a broad range of plant species similar to mycorrhizal symbiosis[2]. In recent decade, much investigations have been performed to study the positive effects of the application of root endophytic fungus (Serendipita indica) on improving growth properties and yield performances under non-stress conditions as well as increase resistance or tolerance under biotic and abiotic stress conditions in different plants (Liu et al., 2020). To evaluate the effects of S. indica inoculation on some morphological traits of Origanum majorana L., a pot experiment was conducted in a completely randomized design with three replications. Treatments included control (without inoculation) and inoculation with S. indica. The results showed that inoculation with S. indica increased plant height, root length, leaf number, fresh weight of shoot, dry weight of shoot, fresh weight of root, dry weight of root and root volume. Overall, the findings of this study showed that inoculation with S. indica can improve the morphological traits of Marjoram
